Yes, Virginia, there is a traitor

[Ceridwen]

No: HPFGUIDX 159290

pippin:
> > <snip>
> > If Draco didn't know  until then that Dumbledore would be out of 
the castle that night, why wait for an hour in the RoR?  Wouldn't he 
have gotten out of there in case Trelawney came back?
> > 
montims:
> > Maybe he was in Diagon Alley, finalising plans?

Tonks:
> Sorry, that doesn't make any sense. Diagon Alley is in London. Once 
the students are at school the only place they can go is Hogsmead. I 
don't think that Draco would be apperating around and not sure you 
can apparate from just outside the gates all the way to Diagon Alley 
anyway. And it is night. I assume that Diagon Alley is not open at 
night.

Ceridwen:
I think Montims means that Draco used the now-functioning cabinet to 
go to Knockturn Alley in order to contact the DEs assigned to him and 
get the plot started.  Of course Draco can't Apparate out of Hogwarts!

I agree that Diagon Alley is probably not open at night, now that so 
many shops are shut down, and people are afraid of all the things 
which have been happening.  It's probably the same in Knockturn 
Alley, for the same reason, for other reasons (wanting to avoid 
suspicion), or for some combination of reasons.  If Draco did use the 
cabinet to get to Borgin and Burke's, he probably had some agreement 
with the proprietor to do so, set up along with the other 
intimidations he used at the beginning of the story.

A traitor would be interesting and I wouldn't rule it out, since it 
was mentioned (by Sirius?) that no one felt as if they could trust 
anybody else at the height of VWI.  Though, it would make for more 
complications in the story and lengthen the last book so that it 
might as well be released as a 10-volume series.  ;)

Ceridwen.